This invention relates to new N-substituted oxobenzothiazolines and oxobenzoxazolines and to their use in a method of regulating leguminous plant growth as well as to plant growth regulant compositions. New compounds which are useful in regulating plants have become increasingly important as the rapidly increasing world population continues to greatly increase the pressure on available world food supplies. An increase in food production through increased land utilization is not a viable solution to this problem because, although more land can be put into production than is now being cultivated, much of that land is marginal and may, in order to be productive, require substantial inputs of water and fossil fuel energy, which are themselves diminishing resources. As a result, the use of chemicals to produce yield increases through the physiological manipulation of the crop plant offers an important means of increasing crop yield.
It is presently known that certain benzothiazyl compounds possess herbicidal activity. U.S. Pat. No. 3,069,429 discloses the use of certain 4-halogeno-2-oxobenzothiazolin-3-yl acetic acids and their derivatives, such as salts, esters, amides, etc., to kill weeds. U.S. Pat. No. 3,839,349 discloses the use of certain N-substituted benzothiazolines useful as insecticides, fungicides and herbicides. None of these patents, however, disclose the use of the specific N-substituted oxobenzothiazolines or oxobenzoxazolines useful in accordance with the present invention to regulate the growth of plants.
It is further known that certain benzothiazyl compounds possess plant growth regulating activities. For example, Japanese Pat. No. 73/10182 discloses the use of certain N-substituted 2-oxo-3-benzothiazoline compounds as grafting agents for tree root growth. U.S. Pat. No. 3,993,468 and U.S. Pat. No. 4,049,419 disclose the use of certain benzothiazolines as plant growth regulants. Co-pending applications of D'Amico, Ser. No. 861,476 and Ser. No. 861,479, both filed Feb. 16, 1977, disclose N-amides and N-hydrazides of 2-benzothiazoline which are useful as plant growth regulants. However, none of the foregoing disclose the use of the specific novel oxobenzothiazolines or oxobenzoxazolines described by the present invention.